clear all
nntwarn off
format compact

P=-1:.1:-.5;
T=[-.9602 -.5770 -.0729 .3771 .6405 .6600 ];
[R,Q] = size(P);
S1 =13;
[S2,Q] = size(T);
[W1, B1]=nwtan(S1, R);
[W2, B2]=rands(S2, S1);
disp_freq = 100;
max_epoch = 20000;
err_goal = 1e-20;
lr=0.02;
error=[];
A1 = tansig(W1*P,B1);
A2 = purelin(W2*A1,B2);
E = T-A2;
SSE = sumsqr(E);
for epoch=1:max_epoch
    if SSE<err_goal
        epoch=epoch-1;
        break;
    end

 D2 = deltalin(A2,E);
 D1 = deltatan(A1,D2, W2);
 [dW1,dB1] = learnbp(P,D1,lr);
 [dW2,dB2] = learnbp(A1,D2,lr);
 W1 = W1+dW1;
 B1 = B1+dB1;
 W2 = W2+dW2;
 B2 = B2+dB2;

 A1 = tansig(W1*P,B1);
 A2 = purelin(W2*A1,B2);
 E = T-A2;
 SSE = sumsqr(E);
 error=[error SSE];

 if(rem(epoch,disp_freq)==0)
     epoch
     SSE
     plot(P,T,'r',P,A2,'g')
     pause(1e-5)
 end

end